Foundation for gates: solid support for capital construction

The foundation for the gate is just that element, the quality of production of which, in many respects, determines the functioning of the entire system. And if it is enough for an input structure of a standard type so that the side pillars are stable and not deformed, then under the automatic opening system - retractable or hinged - it is necessary to lay the foundation with a much larger safety margin.

In this article I will give general information about the gate foundations, and also tell you how the supporting structures for swing and sliding gates are poured. From my own experience, I can say that this type of task can be solved with my own hands, but I have to work, of course.

The movable part of the gate must rest on a capital basis.

Foundation Functions

The capital base for the entrance gate must be as stable as possible.

Moreover, its underground part performs a number of functions, the main ones among which I would call:

1. Fastening supporting posts or their axial parts in the ground (if the bollard is built of brick around a metal pipe concreted into the ground).
2. Formation of the framework of the gate frame.
3. Load distributionacting on the supporting pillars when opening the sash.
4. Load compensationcaused by the movement of the sliding sash when it is opened.
5. Ensuring preservation of the configuration of the whole structure, prevention of distortions, etc.

Underground part ensures efficient distribution of loads, preserving the geometry of the whole structure

Simply put, for both conventional and automatic gates, a quality base is vital. That is why, even in the simplest situations - as is the case with swing gates - I prefer to lay the foundation with a good margin of safety.

Under the swing design

Preparing to install

The foundation for swinging doors is characterized by simplicity of design. By and large, its underground part is a foundation of supports, metal-concrete, wooden beams or reinforced concrete pillars, which are concrete-concrete into the ground.

The construction of such a foundation is not too complicated, but it is a laborious process. I performed it alone several times, and therefore I can state with full responsibility: the assistant will definitely not interfere.

The depth of the pillars is about 1.5 - 2 m

We begin work with the preparation of recesses in which we will install the pillars:

1. I mark up on the goal line, marking the mounting points of the supports. It is very important that they do not protrude beyond the fence line, otherwise our gates will be displaced.
2. By marking digging nests for the pillars. The depth of each nest should be at least 1.5 m (on difficult grounds - up to 2 m), and the width should be at least 10 cm greater than the width of the pole on the larger side.

Jacks for gate posts can be dug out by hand.

Tip! If there is a possibility, we do not dig a hole, but drill it with the help of special tools. So it will be more expensive (rent gasoline hole is about 400 rubles per day), but much faster.

1. At the bottom of each nest I fall asleep at least 30-40 cm of sand-gravel mixture and tamp it carefully.
2. To ensure maximum stability of heavy supports, it is possible to perform primary concreting, a bay on top of about 10 cm of cement based M150 - M200 mortar.
3. Inside I lay the nests with roofing paper, which protects the underground part of the foundation from soil moisture.

Cooking nest using yamobura

1. If the construction of the gate provides for this, then around the perimeter of each pit I bring a low formwork for pouring the basement part. For the manufacture of formwork using boards with a minimum thickness of 20-25 mm.

Concreting and mounting of supports

In this section, I will tell you how to install supports in the nests and how to properly fill them with a solution.

The optimal algorithm is as follows:

1. Support set in the nest, based on footing or compacted gravel and leveled.
2. If the hinges are already welded on the support, I correct the position of the part so that the hinges look towards the opening.

You can further strengthen the gate post by bracing, as in this photo

1. I install the rope braces, fixing the support in a strictly vertical position. It is also possible to additionally fix the pillars in the pit with the help of stones or pieces of reinforcement - they will additionally strengthen the base.
2. I prepare a mortar based on cement M300 with the addition of sand and gravel. I bring the solution to the consistency of thick sour cream and pour it into the nests around the supports, trying to avoid the formation of air pockets.

Nest with a ruberoid insert, ready for concreting

1. I pierce a layer of concrete with a reinforcing bar several times, releasing the air involved. If there is a possibility, then the solution can be treated with a deep vibrator - so it will be even denser.
2. I check if the supports have shifted during the pouring process, additionally fix them with struts from the boards and leave the concrete to dry.
3. Struts and formwork can be removed after 7 -10 days, and I would advise poles to expose the loads not earlier than in 3 - 4 weeks. The time of polymerisation of concrete is 28 days, and throughout this period it is necessary to ensure that the surface of the mortar does not dry out.

Support pillar in concrete "glass"

If the foundation is cast under a structure with a height of more than 2 m with a sash weight of 200 kg or more, then the supporting parts can be further strengthened:

• to make a foundation on screw piles, screwing the supports into the ground and then pouring them with concrete;
• reinforce metal pillars with brickwork (over the entire height or only at the bottom);
• to connect the underground parts of the supports with a strip foundation with a depth of up to 50-60 cm - this improvised screed will reduce the risk of deformation of the gate to a minimum.

Support with cross tie belt type

Under the sliding design

Markup

The base for sliding gates is a channel, mounted on concrete pillars that are underground. This channel is a support for the sliding part, because it is very important that it be securely fixed on a stable base.

Drawing of the foundation for sliding gates, allowing to calculate the dimensions of the base, starting from the width of the opening

Getting started with design calculations:

1. The depth of embedding the base is usually 1.2 - 1.5 m. I usually work within these limits, using smaller foundations only for very lightweight structures with minimal load.
2. The width of the concrete strip is determined by the channel width: if a 200 mm product is used, the base can be made 400 mm wide. And under two channels of 140 mm I lay the foundation 0.5 m wide.
3. The length of the foundation is usually 1/2 the length of the sliding part. Thus, the foundation for sliding gates with a length of 4 meters must be 2 m or more.

200 mm channel as a detail of the supporting platform

Excavation

Based on the calculations, a foundation scheme is built, which I focus on during excavation, reinforcement and concreting:

1. To begin with, I inspect the site from the side from which the sliding door will be located. If necessary, level the ground and uproot trees and shrubs, otherwise their root system will quickly destroy the concrete base.

Trench under the sliding base

1. Next, from the inside of the fence, I dig a trench, the dimensions of which will correspond to the size of the foundation. The recess under the base can be made either rectangular or U-shaped, with two sockets on the sides.
2. I fill the bottom of the trench with sand, forming a pillow up to 15 cm thick. The sandy base is carefully rammed.

Foundation laying

The basis for a sliding gate with a length of 5 meters must be sufficiently massive and withstand solid loads, therefore, reinforcement and proper concreting are indispensable.

The instruction assumes performance of work according to the following scheme:

1. From a reinforcing bar with a diameter of 12-14 mm I weld or bind a frame, the dimensions of which will be somewhat smaller than the dimensions of the trench.
2. I weld the upper edges of the reinforcement to the lower part of the support channel.
3. I lower the metal structure into the trench, installing it on the supports of solid ceramic brick. I carefully align the frame, focusing on the position of the channel - it should be perfectly horizontal and tightly adjacent to the support column of the fence.

Channel with fittings in trench

1. I prepare concrete from 1 part of cement grade not lower than M300, 3 parts of sand and 4 parts of crushed stone. I dilute the solution with water to a moderate consistency and fill the trench, trying to fill it in such a way that there are no voids under the channel.

Important! Concrete should not break through the metal of the mortgage element, as this places the assembly of the sliding mechanism.

1. Filling is best done in layers: I usually fill the trench in parts of 1/4 and then compacted with a bayonet.

Concrete is best poured in layers

Installation of the gate can be carried out within 10 -15 days after pouring: unlike the swing construction, the loads here will not be able to severely damage the foundation. But it must be remembered that it is better not to use the foundation “in normal mode” because of the complete hardening of concrete.

As in the case of swinging gates, the installation of the foundation can be carried out either using screw piles or by mounting a support platform from a channel to reinforced concrete pillars, buried in the ground.

However, these techniques are rarely used, since, for all their laboriousness, they provide an excess margin of safety. So for ordinary sliding gates, the technology described above is quite enough.

If you try and set the frame level, it turns out perfectly smooth

Conclusion

The foundation for the gate must be durable and reliable, and there is probably no other way except for digging it into the ground and fixing it with the help of reinforced concrete. Yes, this work is laborious, but if you watch the video in this article, and if you have difficult questions you will ask them in the comments, you will be able to avoid all the difficulties, and the result will be quite worthy!